In reinforced concrete construction, steel rebar has been the standard for decades.
However, in marine environments, chemical plants, and regions with deicing salts, corrosion and maintenance costs have led engineers to explore alternatives.
Fiber Reinforced Polymer (FRP) rebar is one such solution—lightweight, corrosion-resistant, and non-metallic.
What is FRP Rebar
FRP (Fiber Reinforced Polymer) rebar is a composite reinforcement material made from continuous high-strength fibers embedded in a polymer resin.
Common fibers include glass (GFRP), carbon (CFRP), basalt (BFRP), and aramid, while resins are typically vinyl ester, epoxy, or polyester.
The fibers provide tensile strength, and the resin matrix binds and protects them from environmental degradation.
Unlike steel, FRP rebar does not rust, is much lighter, and does not interfere with electromagnetic fields, making it ideal for sensitive environments.
How FRP Rebar is Manufactured
The primary production method is pultrusion.
Continuous fiber strands are drawn from spools through a resin bath to achieve complete impregnation.
They are then pulled through a heated die where the resin cures and forms the bar shape.
Surface treatments—such as sand coating or helical wrapping—are applied to improve bonding with concrete.
The cured bars are cut to length or formed into factory-made bends, ensuring consistent size, mechanical properties, and surface finish.
Mechanical Properties and Behavior
FRP rebar is linearly elastic until rupture, meaning it has no yield point and fails in a brittle manner when overloaded.
Its tensile strength is generally high—GFRP typically ranges from 483–690 MPa, while CFRP can exceed that.
However, its modulus of elasticity is lower, with GFRP around 35–51 GPa compared to steel’s 200 GPa.
This lower stiffness means FRP-reinforced concrete may experience greater deflections under service loads.
Its density is about one-quarter that of steel, improving ease of transport and installation.
The non-conductive, non-magnetic nature also allows use in facilities such as MRI rooms and research laboratories.
Advantages of FRP Rebar
The most recognized advantage is corrosion resistance.
FRP rebar is unaffected by chloride-induced rust, making it suitable for bridges, piers, parking garages, and wastewater plants.
Its long service life can offset higher upfront costs by reducing repair and maintenance needs.
The lightweight nature reduces transportation costs and simplifies handling on-site, potentially shortening construction timelines.
Additionally, its electromagnetic transparency benefits structures housing sensitive equipment.
Limitations and Design Considerations
FRP rebar’s lower stiffness can lead to larger deflections and wider cracks, so serviceability often governs design.
Its lack of ductility means sudden failure, requiring careful safety factor selection.
The resin matrix softens under high heat, limiting use in fire-rated structures unless additional protection is applied.
FRP bars cannot be bent on-site after curing; all bent shapes must be factory-made.
Anchorage, lap splicing, and shear reinforcement rules differ from steel and must follow FRP-specific codes such as ACI 440.11 and CSA S806.
Standards and Codes
United States
ACI CODE-440.11-22 – Building Code for Structural Concrete Reinforced with GFRP Bars
AASHTO LRFD Guide Specifications for GFRP-Reinforced Concrete Bridge Decks and Traffic Railings
Canada
CSA S807 – Specification for Fibre-Reinforced Polymers
CSA S806 – Design and Construction of Building Structures with Fibre-Reinforced Polymers
CSA S6 – Canadian Highway Bridge Design Code (Section 16: Fibre-Reinforced Structures)
Typical Applications
FRP rebar is widely used in bridge decks and barriers, marine structures, and parking garages.
In water and wastewater facilities, its chemical resistance ensures long-term performance.
It is also chosen for medical and research facilities where non-magnetic reinforcement is required.
Industrial floors and tanks exposed to corrosive chemicals are another common application area.
Cost and Performance
Although FRP rebar costs more per meter than steel, lifecycle cost analyses often show savings in harsh environments.
By avoiding corrosion damage, it reduces both maintenance frequency and the risk of structural failure.
This is particularly valuable in critical infrastructure where downtime and repairs are costly.
Conclusion
FRP rebar combines high tensile strength, low weight, and excellent corrosion resistance, making it a valuable alternative to steel in many scenarios.
When applied according to dedicated FRP design codes and with proper consideration of its stiffness, ductility, and thermal limits, it can significantly extend a structure’s service life.
For projects in aggressive environments or with special requirements, FRP rebar is a reinforcement option worth serious consideration.
